235–275 GHz (x16) frequency multiplier chains with up to 0 dBm peak output power and low DC power consumption

Wideband x16 multiplier chains targeted for high speed communication and radar applications above 200 GHz are presented in this paper. The x16 topology is based on 4 cascaded Gilbert-cell-based frequency doublers without any hybrids and intermediate drive amplifiers. The low external input frequency (14-17.5 GHz), enables the use of very low-power frequency dividers and also interfacing with commercial synthesisers below 20 GHz. Two versions of the circuit were implemented. Version 1 is a standalone x16 chain and Version 2 is Version 1 plus wideband 3-stage PA. For Version 1, the measured peak output power is -8.5 dBm at 255 GHz with 40 GHz bandwidth (3 dB) and dc power consumption of 0.3 W. For Version 2, the peak output power is 0 dBm at 245 GHz with 30 GHz bandwidth (3 dB) and 0.7 W dc power consumption. These results are single ended on-wafer measurements without dembeding the 2.5 dB loss due to the output pad and balun. The available differential output power, to drive on-chip components like mixers, antennas etc, is -6 dBm for Version 1 and 2.5 dBm for Version 2. Additionally, break out sructures for wideband PAs operating at 240 GHz were characterised. The peak power gain at 240 GHz was 7 and 10 dB for the 3 and 4 stages respectively over a 30 GHz bandwidth. The measured P_sat was 5 dBm at 240 GHz.